Field of the Invention
The present invention relates to audio and video home entertainment equipment typically configured for use in the home.
Discussion of the Prior Art
Many home entertainment enthusiasts have configured audio and video playback systems including several components stacked on or under shelves, stands, carts, cabinets or tables, and these components are usually connected to one another with many signal cables and power cords. A system configured in this way typically includes components for receiving, detecting and demodulating audio and video signals, players for playing various forms of media, video displays and audio amplifiers, processors and two or more speakers. In most conventional systems, components such as an AM/FM radio tuner, digital video disc (DVD) player/recorder, satellite/cable television box, a digital media server and other audio playback components are provided as separate modules, each on its own chassis and in its own enclosure.
The many possible combinations of connections and settings for each component have lead to significant confusion. Polk Audio, Bose and others have answered by integrating DVD players and amplifiers with speakers into a type of system known generically as the “home theater in a box.” But even these integrated systems have disadvantages.
A home entertainment system, generally speaking, is able to read media and to process and amplify signals and to provide audiovisual outputs. A home entertainment system need not be located in a home. A home entertainment system may be part of a home theater. One definition of a home theater is a home entertainment system that provides an experience similar to viewing in a cinema, namely brilliant, sharp, large video images with enveloping surround sound. A home theater system generally comprises a screen display, a surround sound system and a source or sources for movie content (e.g., a DVD player) along with audio speakers and visual displays. For purposes of the present description, the terms “home entertainment system” and “home theater” are synonymous.
In one popular configuration of home entertainment system, a television set or other video monitor is featured as a center-piece. In this configuration, the television set is supported on a stand. The stand further comprises shelves, usually below the surface that supports the television set. Alternatively, a home entertainment system may comprise a home entertainment unit rather than a stand. A typical home entertainment unit is a piece of furniture comprising a rectangular enclosure in which shelves are mounted. The various components are supported on the shelves. A typical system may also comprise a radio tuner, television set or television tuner and monitor, audio amplifier, audio preamplifier or “surround sound” unit, a video disc player, and speakers including one or more subwoofers (low frequencies), midbass drivers (mid bass frequencies), midrange drivers (mid frequencies), and tweeters (high frequencies) which are optionally included in a center channel, left front channel, right front channel, and two or more surround or rear channel speaker units. An example of such a television stand is illustrated in U.S. Pat. No. 5,216,211. It is noted that the terms high, mid and low frequency are relative, and do not necessarily specify a particular range of frequencies. Audio environments utilize a number of speakers which interact. Generally there are left, center, right, left rear, right rear and subwoofer speakers. Newer arrangements comprising additional speakers are coming into use.
In prior systems, the electronics modules and the subwoofer units have not been integrated. One disincentive for such integration is the mechanically deleterious effects on electronics modules of vibrations and heat generated when a subwoofer is energized.
Another shortcoming of the prior art is in the placement of the center channel loudspeaker. The center channel is a loudspeaker system that may comprise of a plurality of drivers reproducing a center frequency range, also referred to as the center channel. The center channel frequency range sent by a surround sound processor is the range in which voices and most musical tones fall. Different manufacturers specify different frequency ranges for the center channel. However, one nominal center channel range is 100 Hz-20 KHz. Center channel speaker units have not been adequately integrated into stands and home entertainment units. They may be supported on a stand.
U.S. Pat. No. 6,672,465 discloses a television stand having an upper surface to support a television set and a lower shelf that can support entertainment modules. A shelf intermediate the lower shelf and the upper surface supports and magnetically shields a center channel speaker unit. This construction requires that one shelf be dedicated to the center channel speaker unit. The illustrated center channel speaker unit is constrained to have a width less than that of the shelf. Size constraints of the center channel also constrain the level of acoustical power that can be supplied from the center channel. To produce desired sound levels, center channel output must combine both in frequency and sound pressure level (SPL) with outputs from subwoofers. The smaller center channels may not be capable of delivering the same high SPL levels of the subwoofer. Therefore the power that the subwoofer is designed to provide must also be limited to stay at the lower SPL limits of the center channel. If the subwoofer is not limited and continues to be played louder than the center channel, the bass may become overbearing and sound unnatural. The total system performance either suffers by unnatural sound or limited maximum sound output depending on the system design.
Generally, it is difficult to obtain good performance from a small center channel speaker unit (as compared to a larger center channel speaker). “Wife Acceptance Factor” and other constraints tend to limit both the size of the center channel speaker unit and the number of modules that can be stored on the shelves of the television stand. One particular aspect of this shortcoming is that the SPL output of a small bass speaker in the center channel unit must be blended with the output of a subwoofer frequency and SPL. The subwoofer requires floor space in addition to that required by the stand. The small speaker's maximum sound pressure level (SPL) at a low frequency is lower than that of a larger speaker. The level of audio output applied to drive the small speaker must be limited so as not to overdrive the small speaker. The small speaker's limited audio output thus limits performance of the entire speaker array. In smaller designs of center channel speakers, another commonly encountered drawback is that sound must be transmitted from speaker drivers into cabinet walls of the stand, causing further audio degradation.
There is a need, therefore, for a better home theater audio system and support structure for integrating audio and home theater video components which overcomes these problems and provides a simple, attractive and convenient method and support for setting up and operating the multiple speaker channels in a home entertainment or home theater system.